1. Field
The present disclosure relates to an apparatus and method for attaching substrates, and more particularly to a support and lifting mechanism capable of lifting a substrate independently from a chamber that normally holds the substrate.
2. Background
Recently, with development of an information society, requirements for display devices have been diversified. Therefore, various types of display devices have been developed such as a liquid crystal displays (LCDs), a plasma display panels (PDPs), etc. Users of these display devices require superior video quality, light weight as well as large scale. Therefore, there has been recently developed a super large scale LCD having a size of more than 50 inches.
A LCD is a display device which displays information on its screen using anisotropy of a refractive index of a liquid crystal. The LCD is manufactured by adding liquid crystals between two substrates and attaching the two substrates together. One of the two substrates is a driving device array substrate and the other is a color filter (CF) substrate. A plurality of pixels are formed on the driving device array substrate, and each pixel is formed with a driving device such as a thin film transistor (TFT). A color filter layer for realizing color is formed on the color filter substrate, along with pixel electrodes, a common electrode and an alignment film for aligning a liquid crystal molecule.
In a process for manufacturing a LCD display device, it is a very important to attach two substrates together in a precise manner. The apparatus for attaching the substrates has become larger as the display devices have become larger. The substrate attaching apparatus holds an upper substrate and a lower substrate in a chamber which is capable of maintaining a vacuum state. The substrates are held on an upper chamber and a lower chamber, respectively. The substrates are typically carried into an inside of the chamber by a transportation robot. The substrates are received and held by substrate receiving pins provided on the upper chamber and the lower chamber. The substrates are then seated on the upper chamber and the lower chamber.
A plurality of substrate receiving pins are provided for each of the upper and lower substrates, and the pins are uniformly spaced across the entire area of the substrate to stably hold the substrate when in a horizontal orientation. The substrate receiving pins on the upper and lower chambers are provided together with a driving apparatus so that they can be lifted up and down through holes which pass through the upper chamber and the lower chamber. In order to maintain the inside of the chamber in a vacuum state, a sealing member such as a bellows is provided around the through holes and the pins. The bellows maintain the vacuum, but allow the pins to move relative to the upper and lower chambers. The bellows are relatively expensive, and require periodic replacement to ensure that they can continue to keep a good seal around the pins.
As the substrates have increased in size, the number of substrate receiving pins required to hold the substrates has also increased. Consequently, the number of expensive sealing member bellows that are required, and a load of the driving apparatus for moving the pins has increased. In addition, as the number of pins has increased, it has become more difficult to simultaneously drive all of the plurality of the substrate receiving pins so that they maintain precisely the same height.